PROJECT SUMMARY: The goal of this fellowship is to prepare the applicant, Marian Tzuang, for an independent research career focused on developing and disseminating interventions that optimize cognitive function in older adults. To that end, the proposed fellowship consists of two complementary components: (1) a research project that will further our understanding of the role of sleep in cognitive training for older adults; and (2) a training plan comprised of formal coursework, mentorship, data analysis training (including analysis of actigraphy data), refereed publications, and didactic as well as professional-development activities. The applicant will be supported by a strong mentorship team at the Johns Hopkins Bloomberg School of Public Health and the Johns Hopkins School of Medicine with expertise in cognitive aging, preventive interventions, sleep, and advanced statistical methods. The training program will help the applicant: a) develop substantive knowledge in cognitive health and sleep in aging; b) develop strong methodological skills in longitudinal data analysis, moderation and mediation analysis, and handling Medicare/Medicaid claims data; and c) engage in the dissemination of research findings and networking within the broader cognitive aging research community. An increase in age-associated cognitive decline and neurodegenerative diseases such as Alzheimer's disease (AD) is expected with population aging. Cognitive health is a significant public health concern, and there is an urgency to develop accessible, cost-effective interventions to maintain or improve cognitive function at the population level. Cognitive training has demonstrated effectiveness in enhancing cognitive abilities and daily functioning in older adults, and growing evidence indicates that disturbed sleep plays a critical role in cognitive impairment and the development of AD. However, little is known about how cognitive training affects sleep, and the impact of sleep on the effects of cognitive training. Accordingly, the proposed project will examine: 1) the effect of cognitive training on self-reported sleep and daytime sleepiness, and sleep measured by wrist actigraphy; 2) the long-term effect of cognitive training on sleep disorders and sleep-related health services use across the ACTIVE 20-year follow-up, using Medicare/Medicaid claims data; and 3) whether baseline sleep moderates, and improvements in sleep or sleepiness mediate, the effect of cognitive training on cognition. All aims will be investigated with two existing cognitive training trials, Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE; the largest cognitive training trial to date) and ACTIVE Memory Works (AMW; a web-based cognitive training based on the original ACTIVE trial). The proposed research directly addresses the 2016 NIA Strategic Directions for Research on Aging (Goal D-1) that calls for more research on ?promoting healthy cognitive functioning?as well as quality of sleep.? Our findings have the potential to improve the design and the effectiveness of cognitive training that reduces the burden and health services use of age-related diseases (e.g., AD) by better understanding of the role of sleep.